1. Field of the Invention
The invention relates to a device for the false-twisting of thread by using friction disks. More specifically, the invention relates to defined combinations of disks for false-twisting thread.
2. Description of the Prior Art
German Application DE OS No. 25 27 216 describes an example of a disk combination with two shafts in which a thread guide disk must be arranged in a prescribed manner on one of the shafts. This arrangement of the disks is customary throughout the world and does not result in any problems when operated at the speeds of rotation and the withdrawal speeds used prior to the present time.
It is also conventional to operate with a plurality of thread guide disks on the thread inlet side, as shown in FAG publication No. DB 849, a publication of the assignee hereof. For clockwise rotating disks, each of the thread guide disks is strictly arranged in the clockwise direction from the preceding disk, for operating under certain given conditions, such as speed of rotation of the disks, nature of the disks, speeds of withdrawal and thread supplies. Such an arrangement has been used to obtain the required quality of final thread.
German Application DE OS No. 26 58 034 describes an inlet or outlet disk as a thread guide disk without indicating a definite arrangement of the disk within the unit. Furthermore, the curved contact surfaces in a heating body have direct contact with the thread. Traces of finishing agents are deposited on the curved contact surfaces, which necessarily contributes to agitating the movement of the thread. Up to now, these deposits of finishing agents have not contributed to any particular disturbances in the movement of the thread at the ordinary withdrawal speeds, which remain below a maximum of 600 meters per minute. At higher speeds, however, the deposits cause the thread to become very agitated.
The movement of the thread may be stabilized by thread guide disks arranged on the inlet and/or the outlet side of the pathway of the thread across the array of disks. Conventional disk combinations have as many as ten or more working disks for false-twisting the thread. In addition, there may be one, two or even three guide disks which are combined in series on the inlet side before the thread reaches the working disks. For clockwise rotating disks, each of the thread guide disks in the pathway of the thread across the disks, is always arranged in the clockwise direction of rotation from the preceding disk, as shown in FIGS. 1-3 hereto. As shown in FIG. 3, when one disk is used, it is mounted on shaft 3. When two disks are used as shown in FIG. 2, the first is mounted on shaft 2 and the second on shaft 3, clockwise from shaft 2. When three thread guide disks are used, as shown in FIG. 1, the third disk is arranged on shaft 1 clockwise from shaft 3. Only one thread guide disk is conventionally used on the thread outlet side.
Each combination of disks is described by an abbreviation. For example, if five working disks are used, the combinations described above could be described by the following abbreviations:
(A) 1-5-1 PA1 (B) 2-5-1 PA1 (C) 3-5-1
In each abbreviation, the first number indicates the number of thread guide disks on the inlet side, the second number the number of working disks on the outlet side of the inlet guide disks and the third number the number of thread guide disks on the outlet side of the working disks.
All of these combinations are used throughout the world for different threads and do not result in any particular difficulties with thread withdrawal speeds not exceeding 600 meters per minute.
Recently, there has been demand for higher withdrawal speeds, of 800 meters per minute and more. At these speeds, the thread movement can no longer be stabilized with only the thread guide disks described above. Although the thread can be caused to start up with one disk, its movement remains very agitated and this leads to frequent breaks in the thread. When two disks are used, it is barely possible to start up the thread, particularly if the working disks are made of a soft material. When three thread guide disks or working disks of soft material are used, it is impossible to start up the thread.
In all three cases indicated, the combination of guide disks results in agitation of the thread and does not allow the movement of the thread to stabilize. The thread movement cannot be stabilized even by using more than five working disks.